Pesticides provide important public health benefits including control of malaria and dengue-carrying mosquitoes. However many are neurotoxins that are acutely toxic at high doses and have the potential to exert more subtle effects at lower levels, including exposures in utero and during infancy. Our long-term objectives are to investigate associations between early pesticide exposures and adverse neurodevelopmental outcomes in a prospective birth cohort in Chiang Mai Province (Thailand) and help build capacity of Thai researchers to conduct innovative pesticide exposure research with significant public health implications. We hypothesize that pesticide exposures of pregnant women in Chiang Mai Province are significantly greater than exposures of women in developed countries, while exposures to other neurological insults are low, making this population uniquely suited to the study of pesticides and neurodevelopment. During the R21 period we will collect samples of maternal blood and urine, and umbilical cord blood from a pilot cohort of 50 women receiving monthly routine pre/antenatal care at Fang Hospital in Chiang Mai Province. These will be analyzed for representative pesticides to test our initial assumptions and to evaluate the magnitude, timing, and duration of fetal and infant exposures in this population. We will also extract routine maternal and birth outcome data from prenatal care and labor and delivery records and administer a simple neurological examination among infants born to these mothers. The pilot data will be used to calculate sample size for a larger birth cohort investigating early exposures and neurodevelopmental outcomes. Capacity building milestones will be integrated into each project activity. This pilot research will provide the foundation required to establish a large scale cohort for studying the neurodevelopmental outcomes associated with early pesticide exposures in a population at risk of life-threatening mosquito-borne illness, and help Thai and other women achieve a more healthful balance between the benefits and risks of pesticide use in their communities. PUBLIC HEALTH RELEVANCE: Pesticides are important public health tools for controlling insect-borne diseases and ensuring adequate supplies of healthful foods. However, recent findings from three U.S. studies show adverse associations between low-level pesticide exposures in early life and neurological and neurocognitive development. The proposed Chiang Mai study would provide the most complete characterization to date of potential fetal dose across critical windows of neurodevelopment and help increase scientific understanding of how pesticides influence long-term brain health.